1. Field of the Invention
The present invention relates generally to fasteners, and, more particularly, to a new and improved clinch staple and to a new and improved method of making assemblies of such clinch staples that enables the staples to be more readily manufactured and clinched into workpieces.
2. Description of the Prior Art
Clinch staples may be used to fasten two workpieces together. For example, a lattice may be formed of two thin strips of wood that are fastened together where they intersect. While the strips of wood tend to be thin, conventional straight leg staples may not be suitable for fastening the wood strips together because the legs tend to be too short. Consequently, clinch type staples having longer legs are used. The longer legs can be driven through both pieces of wood with the ends of the legs turned back or clinched into the wood when they strike a flat metal anvil situated below the pieces of wood.
In order for the legs to be deflected inwardly or toward each other as they are driven into the workpieces, the outside surfaces of the distal ends of the legs of the clinch staples are beveled. However, some provision must be made to assure that the legs are separated from one another as they are so deflected or they will contact or interfere with each other as they are being driven back into the workpieces after contacting the anvil. While oppositely directed, saw-toothed configured ends on legs of clinch staples tend to insure that the legs will not interfere with each other as they are being clinched into workpieces, such staples cannot be readily and economically manufactured.
A staple is a formed wire fastener having a generally U-shape configuration with parallel legs projecting perpendicularly from each end of a base or bight portion of the staple. Such staples can be economically fabricated and formed into assemblies of staples by means of automated manufacturing and packaging equipment. For example, reference is made to Kerrigan et al. U.S. Pat. No. 5,035,040 that in part discloses a method of manufacturing of another type of fastener, i.e., hog ring fasteners. The staples that are the most economical to manufacture are those that are formed with points at the end of each leg that are formed by bevelling the end of the legs along planes perpendicular to the plane in which the base and legs of the staple lie. These points at the end of the staple legs are typically referred to as "C" points (a modified version of a "C" point--sometimes referred to as a "CO" point--results when only the outside surface of the end of the staple leg is bevelled). However, problems occur when conventional clinch type of staples having this type of modified "C" point or "CO" point are clinched into a workpiece because the legs of the staples will tend to contact or interfere with each other as the staples are being clinched into the workpieces. Staples can be provided with offset points bevelled in the transverse direction (typically referred to as a "D" point) so that the ends of the legs have a saw-toothed configuration. When the saw-toothed ends are formed in the opposite directions on each leg of the staple, the legs will be deflected from each other as they are being clinched into the workpieces and therefore will not interfere with each other. Unfortunately, the forming of such points requires a more expensive manufacturing process.
Many staple type of fasteners are made in a multi-wire process in which numerous wires are fed side-by-side in a flat plane to bonding, cutoff and forming stations. This is an economical and efficient process for producing staples with a "C" point where the ends of the staple legs are bevelled generally perpendicular to the plane of the fastener. This type of point is formed by pinching off a blank from the flat array of adhered wires prior to forming the wires into the final U-shape configuration of the staple. The blank is rectangular and the legs are formed by bending the blank to make right angle corners perpendicular to the sides of the blank. However, saw-tooth, offset points at the ends of the legs of clinch staples cannot be readily formed using this manufacturing process and consequently, this more economical manufacturing process has not been used for the manufacture of clinch type of staples having "D" points.